Food trucks have proliferated in Austin as a growing number of entrepreneurs seek to sell food while maintaining relatively low overhead costs. The number of mobile food permits issued by the city grew from 648 in 2006 to 1095 in 2009. Many more food trucks have opened in the last six months, and those owners have not yet had to endure the slowdown that comes with Austin's winter.

"It definitely takes its toll this time of year for every food trailer," Bits and Druthers owner Mike Kelley told KUT News. "Because Austinites can deal with the heat, but they can't deal with the cold."

Kelley says cold weather can cut sales by 60 percent. "We can easily go from a $150 day to a $400 day with good weather," he said.

Bits and Druthers is located in a trailer food court called The East Side Drive In, located on E. 6th and San Marcos Streets. Kelley says the trailers cooperate to build an environment that is as warm and inviting as possible by building a camp fire and installing heat lamps.

Other food truck operators adjust their menus for the weather, like Crystal Handy, who owns Cloud 9 Cotton Candy on N. Lamar Blvd.

"I wasn't serving hot drinks at first, but it was so cold, I had a few people asking for them," Handy said. She started selling drinks like hot chocolate "to make it a great day for people who are freezing but want to have something inside their stomach that makes them happy and comfortable."

It's not always economically feasible for food trucks to stay open when the temperature drops below a certain threshold.

"If it's below 50 degrees and the sun's not out, there's no business," Sam Raver, owner of Wurst Tex on South Congress, said.

"We are burning propane. We are paying for it every day. We get fresh bread baked for us every day. Do we really want to keep that standing order going?" he said.

Raver says he already closed for one stretch this month because of cold weather. But he and his business partner used the time to research deep fryers.

"By week's end, we had completely set ourselves up to start making french fries, so we made the most of our downtime," he said.